Knuckle Arm

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The "Knuckle arm" (steering arm) is sandwiched between the Ball Joint and the strut assembly.

Overview

There is only one size for B110, the 45mm strut type. But it comes in two versions: 1970-1975, and 1976-up.

photo

H10 for small-bolt-pattern balljoint
H74 for large-bolt-pattern ball joint

casting marks identify

H74
 

W50

Datsun knuckle arms come in two basic sizes, 75mm & 80mm:

• 75mm narrow bolt spacing for 45mm strut tubes (used by B110)
• 80mm wide bolt spacing for 50.8 mm strut tubes (used by most other Datsuns including 280ZX)
• 91mm spacing on 240Z

Additionally, the size of the taper hole for the ball joint is important.

• B110 and B210 and B310 small uses the small taper
• Some B310 use a large taper

Then there is the length of the arm -- long arm give a slower steering response, but less effort is required to turn the wheels. Shorter arms give faster response.

Change the length of the steering arm without changing the steering idle arm length will impact the front suspension bump steer characteristics.

Short-arm Modified for use with 2" struts

The large-size B310 arm (commonly used when swapping struts) will change your 15:1 steering to an effective 16:1 as the arm is 7% longer. Even worse, when putting 2" struts in a 45mm B310 vehicle, the stock B310 16.4:1 steering will effectively turn into 17.6:1.

Comparison

It seems B310 with W5000/W5060 steering arm uses the same size tie-rod ends as the smaller units (B110 and B210).

* B310 small: rounded
  
* B310 large: knobbed
  

Knuckle Arm

B120 early +H1000/H1025 rod assy
H1000/H5000

B120 7510- +H1025 rod assy
H7400 -8507
H7440 8508-
   

B210 early +H5025
H5000
H7400 late van

B210 late +H5025 rod assy
H7400

PB210/USA B210 +H5800 rod assy
U0101

B310 +W5025 rod assy
H7400 regular cars
   
W5000/W5060 power cars

B310 Steering Knuckle Arms
:post

B310

Part Numbers

steering arm
40052 = Knuckle Arm RH 
40053 = Knuckle Arm LH

Knuckle Arm RH
* B10: 40052-18000 (different from newer models)
* B110: 40052-H1000 < 40052-H5000
* PB110: 40052-H2501
*   510: 40052-H2501 from 1972 510 > 40052-H2500 > 40052-A8600
* B120: 40052-H5000 to 1974
* B120: 40052-H7400 7510- <> 40052-H7440
* B210: 40052-H5000 (74-75 A12)
* B210: 40052-H7400 (1976-up A engine, except USA)
* B210: 40052-U0101 (USA, also PB, also L16)
* B310: 40052-W5000 (All US, all A15, most A14) <> 40052-W5060
* B310: 40052-H7400 (A12, A13, and budget A14 models)
* A10: 40052-W5000 ALL <> 40052-W5060

W50

* 1977-1981 A10 Stanza/510
* 1978-1982 B310 fitted with 13" wheels

B310

CANADA B310
H74 - A12A cars
W50 - A14/A15

JAPAN B310

40052-H7400 ARM-KNUCKLE RH
  ALL round headlight except GX#,Wagon
  S,K.A12A/A13 square headlight
  Van
40052-W5000 <> 40052-W5060
  GX# round headlight (OPTION)
  S,K.A14/A15 square headlight
  Wagon
   
USA B310
W50 - all [including A12A-powered cars]

Compare W50 arm use with the 13" wheel fitment
WHEEL ASS'Y-ROAD B310 JAPAN
12 x 4J GRAY
12 x 4J SILVER
13 x 4.5J SILVER
  40300-W8300 S,K,W square headlight S/# 40300-W5700
              GX# round headlight
              W.GL round headlight
  40300-U7400 W.DX round headlight
13 x 5 alloy Type B 40300-U7527/40300-U7528 (W/KEY)
  OPTION for W
  OPTION for GX round headlight
  OPTION for S,K.A14/A15
13 x 5 alloy Type C 40300-W6027/40300-W6028 (W/KEY)

Spacers

When Lowering the front suspension, if going ultra-low, strut spacers (roll center adapters) are used. They are intended to correct the lower arm angle when the vehicle height is dropped to address the change in front roll instant center.

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